Project Summary The broad, long-term goal of this program of research is to reduce underage drinking and the negative associated consequences. To achieve this goal, this project will examine the efficacy of a web-based feedback program delivered in the school setting for high school seniors. Numerous studies support the efficacy of interventions in delaying the initiation of alcohol use in middle school and early high school or reducing heavy drinking in college. Studies evaluating the efficacy of interventions for teens age 16 and older, however, are limited despite data indicating high school seniors are particularly vulnerable to alcohol associated risks. While interventions for younger adolescents are generally time intensive skill building programs, those for college students tend to be brief normative feedback interventions. Programs developed for younger adolescents may be less relevant for older teens as a greater percentage of this group may use alcohol and may not be receptive to strategies such as peer refusal skills. In contrast, heavy drinking in college is often an extension of drinking patterns established in high school. Thus, rather than selecting an upward adoption of a program developed for younger adolescents, we selected a downward adoption of a brief intervention developed for college students. Specifically, we chose a web-based feedback program as this type of intervention is inexpensive, easy to disseminate, and requires little training. It is not clear, however, if this approach will be effective with high school students, or subgroups of students, who may respond differently to normative feedback than college students. Thus, we aim to assess not only the efficacy of a brief web-based intervention, but also to identify groups of students for whom the intervention is more or less effective, as well as examine reasons why some students may be more or less responsive to this approach. The aims of the research are 1) to evaluate the efficacy of a web-based intervention compared to an assessment-only control condition on reducing drinking and the negative associated consequences among high school seniors using a longitudinal design (6 weeks and 6 months) and 2) to explore how the intervention may need to be modified to be most effective for this age group by examining moderating factors (e.g. baseline drinking, socio-emotional maturity, sex, college-bound status) and mediating variables (e.g. peer drinking norms, alcohol beliefs, alcohol expectancies) to identify subgroups for whom the intervention may be more or less effective and the processes by which the intervention impacts drinking outcomes, thereby providing information on how this intervention may need to be modified for this age group.